The overall goal of this proposed research is to develop a novel "co-culture" system for in-vitro studies of parenchymal-mesenchymal cell interactions. Parenchymal-mesenchymal cell interactions are known to play a vital role in: (i) normal physiology of many organ systems; (ii) pathophysiology of certain diseases; (iii) wound healing and angiogenesis; (iv) developmental biology; (v) cancer; and (vi) tissue engineering. The exchange of information between heterologous cells may occur by direct contact at the cell membrane, by freely diffusible factors with long and short half-lives, and by modification of the intercellular matrix through secretion of insoluble factors. These complex cell communication pathways depend on local cell densities, total cell number, and/or extent of cell contact. Unfortunately, traditional co-culture systems to investigate heterologous cell interactions have been limited by the inability to vary local cell density independently of the cell number, and exhibit inherent variations in the distribution of cell contacts over a population of cells. The investigator will use techniques developed for the microfabrication of electronic devices to create mosaic patterns of two cell types on tissue culture surfaces with precisely controlled heterologous cell interactions. In Specific Aim 1, two-dimensional tissue culture substrates will be developed. This approach will enable one to study heterologous cell interactions in the presence of direct contact between the two cell types. In Specific Aim 2, three-dimensional microtextured tissue culture substrates will be fabricated. This technique will enable one to control heterologous cell interaction in the absence of direct contact. The co-culture systems to be used for the proposed studies include hepatocytes/fibroblasts and keratinocytes/endothelial cells. This proposal utilizes a multi-disciplinary approach involving engineering, material science, chemistry, and cell biology to develop a new paradigm for studies of parenchymal/mesenchymal cell interactions. Although the techniques used to obtain the modified tissue culture substrates require access to sophisticated microelectronics equipment, the steps required after the development of various microfabricated tissue culture substrates are straightforward and can be easily performed in any biomedical science laboratory. As a result, the investigators believe that the microfabricated tissue culture substrates will be readily adopted and used by the cell and molecular biology communities.